Conventional two-stroke and four-stroke small utility engines have been widely used in the gardening, the agricultural machinery and in industry applications, such as lawn mowers, chain saws, tillers, generators, portable brush cutters, blowers, etc. The disadvantage of the two-stroke engine is that the engine lubricant is mixed with the fuel, thus significantly increasing the emission of pollutants. As the pollution emission regulations become more and more strict, two-stroke engines are being replaced with four-stroke engines in as many applications as possible. However, the four-stroke engine has a more complicated lubrication system, which makes the engine less functional when operated at an inclined angle. Lubrication becomes the major design problem for every engine manufacturer. At present, only the HONDA Company has mature techniques for the four-stroke engine working at various inclined angles and has put it into mass production, compare EP 835 987. A special oil tank surrounds rotary blades mounted on the crankshaft to create oil mist. Although efficient for its purpose the engine is wider, heavier and more costly than a splash lubricated engine as described below. U.S. Pat. No. 6,213,079 by Fuji Robin shows an engine with a complex and probably vulnerable lubrication system. Especially it involves a complicated system of oil return passages from its rocker arm chamber to its crankcase and its oil tank. The conventional four-stroke small engine uses an oil pump to pump the lubrication oil to lubricate the engine parts (both the automobile and motorcycle four-stroke engines are lubricated by this method). Another lubricating method of the utility engine uses a hook dipping into the oil and splashing the oil to lubricate the engine. However, the splash lubrication also has limitations for engine operation at an inclined angle of the engine.